The District’s standard for water main construction is Class 52 ductile iron pipe. We require 8-inch minimum diameter water mains for all water mains which serve fire hydrants. This size is required in order to carry sufficient water to the hydrant to fight potential fires. Only in the case of a dead-end water main where there is no hydrant, will the District allow the installation of a smaller water main. In this case, the District would require a 6-inch diameter water main.